Are you asking about a basting brush to put sauce on the food? Or a grill brush to clean the grill grates?
I use a silicone brush, think it's a Cuisinart brand.
Grill brush for cleaning...I usually just use brushes that come with the grills I flip, lol. So right now I've got some nice Weber three sided brushes.
For the gas grill with SS rod grates, the CharGon is the way to go.
If the grates are a little nasty, sometimes I cut an onion in half and use a fork to use the onion as a scrubber.
Or you can wad up some foil and use that as a scrubber.